The present invention relates generally to semiconductor devices. More specifically, the invention relates to the inspection of wire bonds for semiconductor devices.
To facilitate discussion, FIG. 1 is a schematic illustration of a wire bonding system 100 that may be used in the wire bonding process. A host server 102 is connected to an Ethernet network 104. The Ethernet network 104 is connected to a first host PC 106, a second host PC 108, an Ethernet hub 110, a third host PC 114, and a fourth host PC 116. A Behavioral-Based Equipment Models (B-BEM) adapter program 112 is run on the Autoline controller 126, manufactured by ESEC of Switzerland. The B-BEM adapter program 112 acts like a driver on the Autoline controller 126 to control the wire bonders. The first host PC 106 is connected to a first wire bonder 120, which is a stand alone wire bonder through an RS232 connection. The second host PC 108 is connected to a second wire bonder 122, which is also a stand alone wire bonder through an RS232 connection. The Ethernet hub 110 is connected to the Ethernet network 104, the Autoline controller 126 and a Xyplex server 124, which is sold by iTouch Communications of Littleton, Mass. and the Autoline controller 126. The Xyplex server 124 is connected to a third wire bonder 128 and a fourth wire bonder 130 through RS232 connections. The third and fourth wire bonders 128, 130 are Autoline wire bonders. The host PC""s are able to communicate to the wire bonders using SEMI Equipment Communication Stardard (SECS). Other WAN, LAN, and standalone system combinations using different protocols may be used to allow a PC to monitor the schedule and processing of a wire bonder.
The first and second host PC""s 106, 108 communicate with the first and second wire bonders 120, 122 respectively directly through the RS232 connections. The third and fourth host PC""s 114, 116 sends messages to the third and fourth wire bonders 128, 130 respectively through the Ethernet hub to the Autoline controller 126, which gates the messages through the Ethernet hub to the Xyplex server 124 and then to the third and fourth wire bonders 128, 130. A reverse path is used by the third and fourth wire bonders 128, 130 to send messages back to the third and fourth host PC""s 114, 116, respectively.
The host PC""s 106, 108, 114, 116 are used to perform analysis for the wire bonders for performance checking and to control the wire bonders 120, 122, 128, 130 and to provide lot management.
To provide instructions for wire bonding a semiconductor chip, a master recipe may first be created for the semiconductor chip. The master recipe specifies the location of each wire bond. Such specification may provide an (x,y) rectangular coordinate for each wire bond. This master recipe may be created and managed by team of qualified recipe administrators. The master recipe is copied to the wire bonders. Since the wire bonders may have an offset, the wire bonders must be xe2x80x9ctaughtxe2x80x9d to compensate for the offset when the bonders are placed in a teaching mode. The offset may be a combination of a translational and rotational shift. The teaching of a wire bonder causes the creation of a slave recipe, which is a combination of the master recipe and the offset particular to the individual wire bonder. Sometimes slave recipes for one wire bonder are used as a starting point recipe for another wire bonder.
In a wire bond process, with the rise of number of bonding wires and bonding diagram complexity, bond program verification after teaching becomes the more and more tedious and time-consuming job. Bond recipe, once created, might be distributed to and re-used on multiple wire bonders for bonding the same device. Human mistakes could be made on the bond position definition during the offset teaching when the original bond recipe is re-used on the other bonders. Subsequently any teaching related mistake could cause very heavy yield loss if the wrong recipe is used and the mistake remains unchecked.
Two traditional methods had been used before for ensuring the rightness of bond program. The first method is to stipulate second party verification procedure after each bond program offset teaching. The verification may be done manually based on the certified bonding diagram on the paper. Obviously this method is neither effective nor productive, in the sense that it still heavily relies on the human judgment and is also very time-consuming. The second method is to make use of the xe2x80x98limited teach functionxe2x80x99 feature provided by the wire bond equipment itself. This approach is to restrict the change of bond positions within a pre-defined limited range area. A password may be used to protect the limit setting. This method again is ineffective in terms of the security control.
It would be desirable to provide an automated bond program verification method.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, a method for checking a wire bonding recipe is provided. Generally, coordinate data of a master recipe is stored. Coordinate data of a slave recipe is stored. The coordinate data of the slave recipe is compared with coordinate data of the master recipe. An error signal is provided if a mismatch is found between the coordinate data of the slave recipe and the coordinate data of the master recipe.
The invention also provides a computer readable medium containing program instructions for checking a wire bonding recipe. The program contains computer readable code for storing coordinate data of a master recipe, computer readable code for storing coordinate data of a slave recipe, computer readable code for comparing the coordinate data of the slave recipe with coordinate data of the master recipe, and computer readable code for providing an error signal if a mismatch is found between the coordinate data of the slave recipe and the coordinate data of the master recipe.
These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures.